Amine-containing polymers are well known for their use as multi functional lubricant additives; e.g., lubricant dispersant-viscosity modifiers. It has been surprisingly found that quinones may be used to modify the properties of the polymers and in so doing modify the lubricant performance of the polymefic additives. Multifunctional viscosity modifiers (MFVM's) or as they are alternatively identified multifunctional viscosity index improvers (MFVI's) are commercially important lubricant additives.
It has been surprisingly found that reacting MFVM's (containing reactive 1.degree. or 2.degree. nitrogens (i.e. amino groups)) with quinones such as benzoquinone, substituted quinones or naphthoquinone, yields products with improved dispersancy and antioxidancy (e.g., thermooxidative stability).
It is known to use polymer additives which are capable of providing more than one function. Thus, for example, U.S. Pat. No. 4,863,623 discloses a multifunctional lubricant additive which is a VI improver, a dispersant, and an antioxidant when employed in a lubricating oil composition. The additive is a reaction product comprising an ethylene copolymer or terpolymer (molecular weight of 5,000-500,000) of a C.sub.3 -C.sub.10 alpha-monoolefin and optionally a non-conjugated diene or triene (e.g., EPDM) on which has been grafted an ethylenically unsaturated carboxylic functional group (e.g., maleic arthydride) which is then further derivatized with an amino-aromatic polyamine compound selected from certain N-arylphenylenediamines, aminothiazoles, aminocarbazoles, aminoindoles, aminopyrroles and others.
U.S. Pat. No. 5,182,041 discloses the reaction product of a polyolefin (molecular weight of 300-3,500) of a C.sub.2 -C.sub.10 alpha-monoolefin and optionally a non-conjugated diene or triene which has been acylated with an ethylenically unsaturated carboxylic functional group and further derivatized with an amino-aromatic polyamine like those disclosed in the '623 patent of the preceding paragraph. The reaction product is disclosed to impart dispersancy and antioxidant properties to lubricating oil compositions.
U.S. Pat. No. 4,248,725 discloses additives having both dispersant and antioxidant activity in lubricating oil compositions. The additives are produced by reacting a dispersant having free &gt;N-H groups (e.g., a substitute succinimide) with an aldehyde and a compound having antioxidant activity and capable of condensing with the &gt;N-H groups in the dispersant and the aldehyde. Mononuclear and polynuclear substituted phenols and secondary aromatic amines are disclosed to be suitable antioxidants.
U.S. Pat. No. 4,517,104 discloses oil soluble viscosity index improving ethylene copolymers, such as copolymers of ethylene and propylene, reacted or grafted in a mineral oil solvent with unsaturated carboxylic acid moleties such as maleic arthydride, thermally or in the presence preferably of a peroxide initiator, and reacted with polyamines having two or more primary amine groups and an alkenyl succinic anhydride. These reactions permit the incorporation of varnish inhibition and dispersancy into the ethylene copolymer while inhibiting cross-linking with resulting viscosity increase, haze or gelling.
U.S. Pat. No. 5,427,702 discloses multifunctional viscosity modifiers comprising a mixture ofderivatized ethylene-alpha-olefin copolymers, A and B. Copolymer A comprises from about 30 to about 60 wt. % monomer units derived from ethylene and copolymer B comprises from about 60 to about 80 wt. % units derived from ethylene. The respective weight percent of ethylene derived monomer units present in copolymers A and B differs by at least 5 wt. %.
U.S. Pat. No. 5,424,367 discloses multiple sequential chemical reactions on a polymeric feedstock carded out in an extruder with multiple reaction zones. Each reaction zone has means for introduction of reagents, for mixing of reagents with polymer and for removal of by/co-products or unreacted reagents.
U.S. Pat. No. 5,030,370 discloses compositions of lubricating oil and amino-substituted polymers (e.g. ethylene alpha-olefin interpolymers substituted by primary amino or secondary amino groups). Preferred amino-substituted interpolymers comprise amino-substituted ethylene propylene norbornene terpolymers. The polymers are disclosed to be oil soluble and useful as viscosity index improver dispersants.
U.S. Pat. No. 5,211,865 discloses lubricating oil compositions exhibiting improved antioxidant properties containing a viscosity index improver-dispersant comprising the reaction products of an ethylene copolymer having a molecular weight of from 5,000-500,000 grafted with ethylenically unsaturated carboxylic acid material, a polyamine having at least two primary amino groups, an aldehyde, a heterocyclic nitrogen reactant having at least an --N(H)-- group in the heterocyclic ring; and optionally a high functionality long chain hydrocarbyl substituted dicarboxylic acid material. Preferred heterocyclic nitrogen reactants are disclosed to be benzotdazole and tolyltriazole.
U.S. Pat. No. 5,2718,56 discloses oil soluble polymers useful as dispersant, viscosity index improver, antiwear and antioxidant additives. The polymers are prepared by reacting a heterocyclic nitrogen compound containing at least one --N(H)-- group in the ring, an aldehyde and an amino-substituted polymer as disclosed above in '370. Preferred heterocyclic nitrogen compounds are disclosed to be benzotriazole and tolyltriazole.
There is a continuing need to develop new additives for fuel and lubricating oil compositions, especially additives which can effectively impart more than one property. An advantage ofmultifunctional additives to the formulator is that two or more discrete additives can be replaced with a single additive, thereby avoiding or minimizing the incompatibility problems and adverse interactions which can often accompany the use of several monofunctional additive components in a composition. The present invention provides additives which act as viscosity modifier-dispersants and provide antioxidancy as well.